1. Field of the Invention
This invention pertains to restraining devices, and more particularly to apparatus for resiliently restraining two bodies to each other.
2. Description of the Prior Art
Various equipment has been developed to restrain an object from moving away from a second object. A well known example of such devices is the elastic tie down. The usual application of a tie down is to resiliently hold a relatively small or light object within a predetermined distance of a larger and heavier body.
An advantage of elastic tie downs is that they are versatile and easy to install. That is because the tie downs can be stretched, within limits, to accommodate variable sizes of and distances between the objects. Further, elastic tie downs permit some relative movement between the restrained objects. In that manner, vibrations and other small relative motions can be accommodated without creating large stresses and subsequent harm to the tie down or to the restrained objects.
On the other hand, most elastic tie downs possess the disadvantage of being yieldable up to their breaking points. That is, as the force tending to separate the restrained objects increases, the tie down continually stretches until it finally breaks. Tie down breakage, of course, completely removes the restraint between the bodies. Even before breakage, however, the two objects may have become so widely separated that damage or other undesirable consequences occur.
To limit the yielding of elastic tie downs, it is known to combine a tension member of fixed length with an elastic member. Under moderate separating forces, the elastic member provides resilient restraint against separation, and the tension member remains slack and inoperative. Upon the separating force attaining a predetermined value, the elastic member becomes stretched such that the tension member is taut and takes over as the restraining member. Examples of such hold-down devices may be seen in U.S. Pat. Nos. 2,991,524; and also in 4,694,541, the disclosure of which is incorporated by reference herein.
Although the aforementioned hold-down devices are generally satisfactory, they nevertheless are subject to improvement and further development.